1. Field of the Invention
The present invention relates to a water base ink for ink-jet recording to be used for an ink-jet recording apparatus, and to an ink-jet recording apparatus.
2. Description of the Related Art
Those known for the printer technique based on the ink-jet recording method include, for example, the bubble method in which an ink is discharged from a minute nozzle by the aid of bubbles generated by rapid heating, and the piezoelectric method in which an ink is discharged from a minute nozzle by using a piezoelectric device which is deformable in accordance with the voltage application. Inks, which have several colors respectively to serve as fundamental colors, are converted into minute droplets of several picoliters to several tens picoliters, and they are selectively landed on the recording paper surface to form an image thereby.
The ink-jet recording method is advantageous in the high letter-printing quality and the high image-printing quality owing to the discharge control of the minute droplets. An image, which has no granular texture, can be formed by landing the several picoliters of the minute droplets on the paper surface highly accurately. However, in order to successfully discharge the minute droplets as described above, it is necessary to adopt a technique for highly accurately controlling the discharge from the sufficiently thin nozzle. In order to achieve the highly accurate discharge control technique as described above, a highly accurate machining technique is required for major portions for constructing, for example, the ink flow passage and the printer head. In general, the material, which is cheap and which can be subjected to the highly accurate machining, is the metal material. Therefore, metal parts are used for major portions of the printer for which the strength and the durability are required.
Most of the ink-jet printers generally use the anionic dye ink in view of the toxicity and the coloring performance on the recording paper. However, the vividness or brilliantness is insufficient depending on the color (especially, in the case of the yellow). It is demanded to obtain a brilliant image as if the image is drawn by a marker pen. In order to satisfy such a demand, it is the best to use a basic dye having brilliant color development such as those used for the marker pen. However, the ink, which is based on the use of the basic dye, has low pH, in which it is feared that metal parts of the printer (including plated parts) may be corroded. Although the printer is constructed such that metal parts are not used for the parts which always make contact with the ink as far as possible, the following problem inevitably arises. That is, a slight amount of the ink is scattered during the printing or during the maintenance for the nozzle, and the ink adheres to the metal parts for constructing the printer, resulting in the corrosion of the metal and the deterioration of the printing stability. Therefore, usually, the basic dye ink should be used on condition that an alkaline pH-adjusting agent is added so that pH of the ink is neutral or alkaline. However, another problem has arisen as follows depending on the type of the pH-adjusting agent. That is, the chromaticness and the color feature of the printed image are changed, and the brilliantness, which is inherent in the basic dye, is spoiled. The present inventors have diligently made the study in order to solve the problem described above. As a result, it has been found out that the chromaticness and the color feature of the printed image are not changed when a pH-adjusting agent having a specified structure is used. Thus, the present invention has been completed.